The discovery of monensin was a significant one. It was the first member of what is now recognized as a class of "polyether" antibiotics. Under the trademark "Coban.RTM.", it is sold as an anticoccidial for use in chickens and turkeys. It is one of the most widely used anticoccidials, the world over. Under the trademark "Rumensin.RTM.", it is sold for use in ruminants, where its effect is to alter the rumen flora, favoring production of propionate over acetate, and thereby achieving increased growth and improved feed efficiency. The relevant patents are U.S. Pat. No. 3,501,568, regarding the compound and its anticoccidial use; and U.S. Pat. No. 3,839,557, regarding use in ruminants. U.S. Pat. No. 3,839,557 is incorporated herein by reference.
The structure of monensin has been known for a long time, and some derivatives have been prepared. None has been the subject of any commercial level of interest.